Materials that convert infrared light into visible light are desirable for use in photocatalysts, solar energy harvesting, deep tissue imaging and phototherapy. Inorganic nanocrystals (NCs) functionalized with energy-accepting dyes form a promising platform to meet this demand. These materials to date have made exclusive use of NCs containing toxic elements, precluding their use in biological or environmentally sensitive applications. Silicon is highly attractive for NC-based upconversion systems as it is both earth-abundant and non-toxic.
Profs. Ming Lee Tang and Lorenzo Mangolini from the University of California, Riverside have developed a method for synthesizing chemically functionalized non-toxic silicon nanocrystals. This technology works by producing silicon NCs with non-thermal plasma synthesis which are then functionalized with triplet acceptors to produce photon upconversion systems. This technology stands out among other NC-based triplet-fusion upconversion systems because when incorporated into aqueous micelles, this system functions indefinitely under anaerobic conditions and for tens of minutes upon exposure to oxygen.
Fig. 1 Schematic of the aqueous photon upconverting micelles.